Interferometric apparatus for detecting 3D position of a diffracting object

ABSTRACT

A position detecting apparatus includes a light source, which supplies a detecting light; a light-collecting optical system which collects the detecting light onto a diffracted light generating portion provided on the object; a light guiding optical system which guides, to a predetermined position, a diffracted measuring light generated from the diffracted light generating portion by receiving the detecting light and a reference light generated from a reference surface by receiving the detecting light; and a photodetector which is arranged at the predetermined position and which detects interference fringes generated by the diffracted measuring light and the reference light. Three-dimensional positional information of, for example, a mask pattern surface or an exposure surface of a photosensitive substrate can be highly accurately detected by a relatively simple construction.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 12/715,227, filed on Mar. 1, 2010, which is a continuation ofInternational Application No. PCT/JP2008/065185, filed on Aug. 26, 2008,and which claims priority to Japan Patent Application No. 2007-220552,filed on Aug. 28, 2007, all of which being incorporated herein byreference in their respective entireties.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a position detecting apparatus, aposition detecting method, an exposure apparatus, and a method forproducing a device. In particular, the present invention relates to theposition detection for a mask or a photosensitive substrate in anexposure apparatus which is usable in the lithography step of producingan electronic device including semiconductor elements, image pickupelements, liquid crystal display elements, thin film magnetic heads,etc.

Description of the Related Art

When a device such as a semiconductor element or the like is produced, aplurality of layers of circuit patterns are formed in an overlapped oroverlaid manner on a photosensitive substrate (substrate such as awafer, a glass plate or the like coated with a photosensitive material).Therefore, in order to perform the relative positional adjustment(alignment) for a pattern of a mask and each of exposure areas of thephotosensitive substrate having been already formed with a circuitpattern or patterns in an exposure apparatus for exposing thephotosensitive substrate with the circuit patterns, it is necessary todetect the two-dimensional position information taken along a patternsurface of the mask and the two-dimensional position information takenalong an exposure surface of the photosensitive substrate. For example,a position detecting apparatus based on the image pickup system has beenhitherto suggested in order to detect the two-dimensional positioninformation about the pattern surface of the mask or the exposuresurface of the photosensitive substrate. In U.S. Pat. No. 5,783,833, forexample, an image pickup element, which is constructed of a CCD camera,is used as an alignment sensor of the off-axis system in order topositionally adjust (align) the mask pattern and the photosensitivesubstrate. A part of the imaging light flux is received by the imagepickup element via a light flux semi-shielding plate.

On the other hand, in order to form a good image (fair image) of a finepattern of a mask on a photosensitive substrate via a projection opticalsystem, it is necessary for the exposure apparatus to detect the focusposition information of the pattern surface of the mask and the focusposition information of the exposure surface of the photosensitivesubstrate taken in the optical axis direction of the projection opticalsystem. In order to detect the focus position information of the patternsurface of the mask or the exposure surface of the photosensitivesubstrate, for example, a position detecting apparatus of thephotoelectric microscope system has been hitherto suggested.

SUMMARY OF THE INVENTION

The position detecting apparatus, of the image pickup system fordetecting the two-dimensional position information about the patternsurface of the mask or the exposure surface of the photosensitivesubstrate, is constructed completely differently from the positiondetecting apparatus of the photoelectric microscope system for detectingthe focus position information about the pattern surface of the mask orthe exposure surface of the photosensitive substrate. In other words, inthe conventional technique, it has been impossible to highly accuratelydetect the three-dimensional position information about the patternsurface of the mask or the exposure surface of the photosensitivesubstrate by using a single unit of any position detecting apparatus.

The present invention has been made taking the foregoing problem intoconsideration, an object of which is to provide a position detectingapparatus and a position detecting method which make it possible tohighly accurately detect, for example, the three-dimensional positioninformation about a pattern surface of a mask or an exposure surface ofa photosensitive substrate in accordance with a relatively simpleconstruction or structure. Another object of the present invention is toprovide an exposure apparatus which makes it possible to highlyaccurately perform the positional adjustment for a pattern surface of amask and an exposure surface of a photosensitive substrate with respectto a projection optical system by using a position detecting apparatuswhich highly accurately detects the three-dimensional positioninformation about the pattern surface of the mask or the exposuresurface of the photosensitive substrate.

According to a first aspect of the present invention, there is provideda position detecting apparatus which detects a position of an object,the position detecting apparatus comprising: a light source whichsupplies a detecting light; a light-collecting optical system whichcollects the detecting light onto a diffracted light generating portionprovided on the object; a light guiding optical system which guides, toa predetermined position, a diffracted measuring light generated fromthe diffracted light generating portion by receiving the detecting lightand a reference light generated from a reference surface by receivingthe detecting light; and a photodetector which is arranged at thepredetermined position and which detects interference fringes generatedby the diffracted measuring light and the reference light.

According to a second aspect of the present invention, there is provideda position detecting apparatus which detects a position of an object,the position detecting apparatus comprising: a light source whichsupplies a detecting light; an illumination optical system whichilluminates, with the detecting light, a diffracted light generatingportion provided on the object; and a photodetector which detectsposition information of a spherical center of a diffracted lightgenerated from the diffracted light generating portion by receiving thedetecting light. The term “spherical center of the diffracted light”refers to the substantial center of the diffracted light generatingportion. In a case that the diffracted light (diffracted light beam)generating portion is a pinhole, the spherical center of the diffractedlight corresponds to the center of the pinhole. The position informationof the spherical center of the diffracted light means information aboutpositional deviation of the spherical center of the diffracted light.

According to a third aspect of the present invention, there is provideda position detecting method for detecting a position of an object, theposition detecting method comprising: collecting a detecting light ontoa diffracted light generating portion provided on the object; detectinginterference fringes generated by a diffracted measuring light generatedfrom the diffracted light generating portion by receiving the detectinglight and a reference light generated from a reference surface byreceiving the detecting light; and determining three-dimensionalposition information of the diffracted light generating portion based onthe interference fringes.

According to a fourth aspect of the present invention, there is provideda position detecting method for detecting a position of an object, theposition detecting method comprising: illuminating a diffracted lightgenerating portion, which is provided on the object, with a detectinglight; detecting position information of a spherical center of adiffracted light generated from the diffracted light generating portionby receiving the detecting light; and determining three-dimensionalposition information of the diffracted light generating portion based onthe position information of the spherical center of the diffractedlight.

According to a fifth aspect of the present invention, there is provideda position detecting apparatus which detects a position of an object,the position detecting apparatus comprising: a light splitter whichsplits a light from a light source into a measuring light directed tothe object and a reference light; an interference optical system whichcauses interference between the reference light and a diffracted lightgenerated from the measuring light irradiated onto a diffracted lightgenerating portion provided on the object; and a photodetector whichdetects interference fringes generated by the interference between thediffracted light and the reference light. The interference opticalsystem may have a first reflecting mirror and a second reflecting mirrorwhich cause the diffracted light and the reference light to be reflectedonto a same optical path. A driving element, which moves the secondreflecting mirror, may be provided on the second reflecting mirror. Thefirst reflecting mirror may be provided on the light splitter. Thediffracted light generating portion may be a pinhole.

According to a sixth aspect of the present invention, there is provideda position detecting method for detecting a position of an object, theposition detecting method comprising: splitting a light from a lightsource into a measuring light and a reference light; generating adiffracted light by irradiating, with the measuring light, a diffractedlight generating portion provided on the object; causing interferencebetween the diffracted light and the reference light; and obtainingthree-dimensional information of the object by detecting interferencefringes generated by the interference between the diffracted light andthe reference light.

According to a seventh aspect of the present invention, there isprovided an exposure apparatus which exposes a photosensitive substratewith a predetermined pattern via a projection optical system, theexposure apparatus comprising: the position detecting apparatus of thefirst aspect or the second aspect which detects, as the position of theobject, a position of a surface of the predetermined pattern or anexposure surface of the photosensitive substrate; and an alignmentapparatus which aligns the surface of the predetermined pattern or theexposure surface of the photosensitive substrate with respect to theprojection optical system based on a detection result of the positiondetecting apparatus.

According to an eighth aspect of the present invention, there isprovided a method for producing a device, comprising: an exposure stepof exposing the photosensitive substrate with the predetermined patternby using the exposure apparatus of the seventh aspect; and a developmentstep of developing the photosensitive substrate exposed in the exposurestep.

In the position detecting apparatus and the position detecting method ofthe present invention, the detecting light (detecting light beam) iscollected onto the diffracted light generating portion provided, forexample, on the pattern surface of the mask or the exposure surface ofthe photosensitive substrate to detect the interference fringes formedby the diffracted measuring light (diffracted measuring light beam)generated from the diffracted light generating portion and the referencelight (reference light beam) generated from the reference surface. Thetwo-dimensional position information of the pattern surface of the maskor the exposure surface of the photosensitive substrate is detectedbased on tilt components of the interference fringes obtained byanalyzing the detected interference fringes. The focus positioninformation of the pattern surface of the mask or the exposure surfaceof the photosensitive substrate is detected based on the focuscomponents of the interference fringes.

As a result, in the position detecting apparatus and the positiondetecting method of the present invention, for example, thethree-dimensional position information of the pattern surface of themask or the exposure surface of the photosensitive substrate can bedetected highly accurately in accordance with the relatively simpleconstruction. In the exposure apparatus of the present invention, thepattern surface of the mask and the exposure surface of thephotosensitive substrate can be subjected to the positional adjustment(alignment) highly accurately with respect to the projection opticalsystem by using the position detecting apparatus which detects thethree-dimensional position information of the pattern surface of themask or the exposure surface of the photosensitive substrate highlyaccurately. Consequently, it is possible to produce the electronicdevice highly accurately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a construction of an exposure apparatusaccording to an embodiment of the present invention.

FIG. 2 schematically shows an internal construction of a mask positiondetecting apparatus shown in FIG. 1.

FIG. 3 shows a situation in which a pinhole is formed as a minutelight-transmitting portion surrounded by a light-reflecting area on apattern surface of a mask.

FIG. 4A shows a situation in which a light shielding member isadditionally provided in an optical path between a light-collecting lensand the mask, and FIG. 4B shows a situation in which the light shieldingmember is arranged to shield about a half of a detecting light whicharrives at the pattern surface of the mask and forms a spot light.

FIG. 5 schematically shows a construction of a light shielding memberhaving a form different from that shown in FIG. 4.

FIG. 6 shows a flow chart illustrating a procedure adopted when asemiconductor device is obtained as an electronic device.

FIG. 7 shows a flow chart illustrating a procedure adopted when a liquidcrystal display element is obtained as an electronic device.

FIG. 8 conceptually illustrates the principle of detection oftwo-dimensional position information of the pinhole.

FIG. 9 conceptually illustrates the principle of detection of focusposition information of the pinhole.

FIG. 10A conceptually shows an interference fringe pattern obtained whenthe positional deviation of a mask M is absent, FIG. 10B conceptuallyshows an interference fringe pattern obtained when the positionaldeviation arises in the X direction of the mask M, and FIG. 10Cconceptually shows an interference fringe pattern obtained when thepositional deviation arises in the Z direction of the mask M.

FIG. 11A shows a protrusion having a reflecting surface, instead of thepinhole; and FIG. 11B shows a recess having a reflecting surface,instead of the pinhole.

FIG. 12 shows a graph illustrating a timing for incorporating theinterference fringe (interference light, interference light beam) into apixel of CCD constructing a photodetector and a reflecting mirrordriving amount brought about by a driving device for a reflectingmirror.

FIGS. 13A to 13D each shows a change of interference fringe patterndetected by the photodetector in accordance with the change of thedriving position of the reflecting mirror.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be explained based on theattached drawings. FIG. 1 schematically shows a construction of anexposure apparatus according to the embodiment of the present invention.In FIG. 1, the X axis and the Y axis are set so that the X axis and theY axis are perpendicular to each other in a plane parallel to a surface(exposure surface) of a wafer W, and the Z axis is set in the normalline direction of the surface of the wafer W. More specifically, the XYplane is set horizontally, and the +Z axis is set upwardly in thevertical direction.

As shown in FIG. 1, the exposure apparatus of this embodiment includesan illumination system 1 which includes, for example, an ArF excimerlaser light source as an exposure light source and which is constructedof an optical integrator (homogenizer), a field diaphragm, a condenserlens, etc. The illumination system 1 illuminates a mask (reticle) M onwhich a pattern to be transferred is formed, with an exposure light(exposure light beam) radiated from the light source. The illuminationsystem 1 illuminates, for example, an entire pattern area having arectangular shape of the mask M or a slit-shaped area which is includedin the entire pattern area and which is long in the X direction (forexample, a rectangular area).

The light (light beam), which is transmitted through the mask M forms,via a projection optical system PL having a predetermined reductionmagnification, an image of the pattern (pattern image) of the mask M ina unit exposure area of the wafer (photosensitive substrate) W coatedwith a photoresist. That is, the mask pattern image is formed in arectangular area which is similar to the entire pattern area of the maskM or a rectangular area (still exposure area) which is long in the Xdirection, in the unit exposure area of the wafer W so that the areaoptically corresponds to the illumination area on the mask M.

The mask M is held in parallel to the XY plane on a mask stage MS. Amechanism (for example, a linear motor), which finely moves the mask Min the X direction, the Y direction, and the direction of rotation aboutthe Z axis, is incorporated into the mask stage MS. A movement mirror MMis provided on the mask stage MS. A mask laser interferometer MIF, whichuses the movement mirror MM, measures, in real-time, a position of themask stage MS (and consequently the mask M) in the X direction, the Ydirection, and the direction of rotation.

The wafer W is held in parallel to the XY plane on a Z stage 2 via awafer holder (not shown). The Z stage 2 is attached onto an XY stage 3which is movable along the XY plane parallel to the image plane of theprojection optical system PL; and the Z stage 2 adjusts a focus position(position in the Z direction) and an angle of inclination (inclinationof the surface of the wafer W with respect to the XY plane) of the waferW. A movement mirror WM is provided on the Z stage 2. A wafer laserinterferometer WIF, which uses the movement mirror WM, measures, inreal-time, a position of the Z stage 2 in the X direction, the Ydirection, and the direction of rotation about the Z axis. The XY stage3 is placed on a base 4; and the XY stage 3 adjusts the position of thewafer W in the X direction, the Y direction, and the direction ofrotation.

The output of the mask laser interferometer MIF and the output of thewafer laser interferometer WIF are supplied to a main control system 5.The main control system 5 controls the position of the mask M in the Xdirection, the Y direction, and the direction of rotation based on themeasurement result of the mask laser interferometer MIF. That is, themain control system 5 transmits the control signal to the mechanismincorporated into the mask stage MS; and the mechanism finely moves themask stage MS based on the control signal, to thereby adjust theposition of the mask M in the X direction, the Y direction, and thedirection of rotation.

The main control system 5 controls the focus position and the angle ofinclination of the wafer W in order that the surface of the wafer W isadjusted and matched with respect to the image plane of the projectionoptical system PL (in order that the surface of the wafer W iscoincident with the image plane) in the auto-focus manner and theauto-leveling manner. That is, the main control system 5 transmits thecontrol signal to a wafer stage driving system 6; and the wafer stagedriving system 6 drives the Z stage 2 based on the control signal, tothereby adjust the focus position and the angle of inclination of thewafer W.

The main control system 5 controls the position of the wafer W in the Xdirection, the Y direction, and the direction of rotation based on themeasurement result of the wafer laser interferometer WIF. That is, themain control system 5 transmits the control signal to the wafer stagedriving system 6; and the wafer stage driving system 6 drives the XYstage 3 based on the control signal, to thereby adjust the position ofthe wafer W in the X direction, the Y direction, and the direction ofrotation.

In the step-and-repeat system, one unit exposure area, which is includedin the plurality of unit exposure areas set laterally and longitudinallyon the wafer W, is subjected to the full field exposure with the patternimage of the mask M. After that, the main control system 5 transmits thecontrol signal to the wafer stage driving system 6 so that the XY stage3 is step-moved along the XY plane by the wafer stage driving system 6.Accordingly, another unit exposure area of the wafer W is positionedwith respect to the projection optical system PL. In this way, theoperation, in which the unit exposure area of the wafer W is subjectedto the full field exposure with the pattern image of the mask M, isrepeated.

In the step-and-scan system, the main control system 5 transmits thecontrol signal to the mechanism incorporated into the mask stage MS, andthe main control system 5 transmits the control signal to the waferstage driving system 6 so that the mask stage MS and the XY stage 3 aremoved at a velocity ratio corresponding to the projection magnificationof the projection optical system PL, while one unit exposure area, amongthe plurality of unit exposure areas, of the wafer W is subjected to thescanning exposure with the pattern image of the mask M. After that, themain control system 5 transmits the control signal to the wafer stagedriving system 6 so that the XY stage 3 is step-moved along the XY planeby the wafer stage driving system 6. Accordingly, another unit exposurearea of the wafer W is positioned with respect to the projection opticalsystem PL. In this way, the operation, in which the unit exposure areaof the wafer W is subjected to the scanning exposure with the patternimage of the mask M, is repeated.

That is, in the step-and-scan system, the mask stage MS and the XY stage3 as well as the mask M and the wafer W are synchronously moved(subjected to the scanning) in the Y direction which is the short sidedirection of the still exposure area having the rectangular shape(generally the slit shape), while performing the position control of themask M and the wafer W by using the wafer stage driving system 6, thewafer laser interferometer WIF, etc. Accordingly, the area, which hasthe width equal to the long side of the still exposure area and whichhas the length corresponding to the scanning amount (movement amount) ofthe wafer W, is subjected to the scanning exposure with the mask patternon the wafer W.

The exposure apparatus of this embodiment is provided with a maskposition detecting apparatus 11 which detects the three-dimensionalposition information (position in the X direction, position in the Ydirection, and position in the Z direction) of the pattern surface ofthe mask M, and a wafer position detecting apparatus 12 which detectsthe three-dimensional position information (position in the X direction,position in the Y direction, and position in the Z direction) of theexposure surface of the wafer W. The mask position detecting apparatus11 is attached, for example, to the illumination system 1, and the waferposition detecting apparatus 12 is attached, for example, to theprojection optical system PL. The mask position detecting apparatus 11and the wafer position detecting apparatus 12 are basically constructedidentically with each other, and provide mutually identical functions.In the following description, taking notice of the mask positiondetecting apparatus 11, an explanation will be made about theconstruction and the function of the position detecting apparatusaccording to this embodiment.

FIG. 2 schematically shows an internal construction of the mask positiondetecting apparatus shown in FIG. 1. With reference to FIG. 2, the maskposition detecting apparatus 11 of this embodiment principally includes,for example, a He—Ne laser light source 21 which is provided as a lightsource which supplies a detecting light or detecting light beam(measuring light or measuring light beam), a beam splitter (lightsplitter) 22 which splits the detecting light into the measuring lightand a reference light, a light-collecting lens 23 which collects themeasuring light onto a pinhole PH, a reflecting mirror 24 which reflectsthe reference light, a photodetector 26, a relay lens system 25 whichguides the reference light reflected by the reflecting mirror 24 and adiffracted light (measuring light) generated from the pinhole to thephotodetector 26, and a signal processing system 27. A driving device 24a such as a PZT element or the like, which drives the reflecting mirror24 in the XYZ directions, is provided on the reflecting mirror 24. Thedriving device 24 a is controlled by the main control system 5 connectedthereto. The detecting light from the light source 21 is converted intoa substantially parallel light by an unillustrated collimator lens, andthen the detecting light comes into the beam splitter 22. The exposurelight, which is taken out from the illumination optical path of theillumination system 1 of the exposure apparatus, can be also used as thedetecting light. A part of the detecting light (measuring light), whichis allowed to come into the beam splitter 22, is transmitted through thebeam splitter 22, and the part of the detecting light forms a spot lightin a minute area (for example, a circular area) including the pinhole PHprovided on the pattern surface of the mask M, via the light-collectinglens 23. Another part of the detecting light (reference light), which isallowed to come into the beam splitter 22, is reflected by thereflecting surface provided in the beam splitter 22, and the anotherpart of the detecting light is directed to the plane reflecting mirror24 which has the reflecting surface parallel to the YZ plane.

As shown in FIG. 3, the pinhole PH is formed as a minutelight-transmitting portion (for example, a circular area) which issurrounded by a light-reflecting area 31 on a pattern surface PP of themask M. Specifically, a diameter D of the pinhole PH is designed to besmaller than λ/(2×NA) provided that λ represents the wavelength of thedetecting light and NA represents the numerical aperture of the lightflux forming the spot light on the pattern surface PP of the mask M(numerical aperture of the light-collecting lens 23) so that thediffracted light, which is generated from the pinhole PH, issubstantially a spherical wave. As shown in FIG. 3, a reflecteddiffracted light L2 is generated from the pinhole PH by receiving thedetecting light L1. The diffracted light L2 from the pinhole PH travelsas the measuring light and returns to the beam splitter 22 via thelight-collecting lens 23, and the diffracted light L2 is reflectedtoward the relay optical system 25 by the reflecting surface provided inthe beam splitter 22.

On the other hand, the another part of the detecting light, which isreflected by the beam splitter 22, is reflected by the reflectingsurface (reference surface) of the plane reflecting mirror 24, and theanother part of the detecting light returns as the reference light tothe beam splitter 22. As described later on, the plane reflecting mirror24 is finely moved mainly in the optical axis direction (X direction) bythe driving device 24 a provided on the plane reflecting mirror 24. Forexample, a corner cube prism can be also used instead of the planereflecting mirror 24. Also in such a case, it is desirable to provide adriving system for finely moving the reflecting surface. The measuringlight reflected by the beam splitter 22 and the reference lighttransmitted through the beam splitter 22 come, via the relay opticalsystem 25, into the photodetector (area sensor) 26 such as CCD or thelike. The reflecting surface provided in the beam splitter 22 and theplane reflecting mirror 24 constitute an interference optical system.The interference fringes, which are formed by the interference betweenthe reference light and the measuring light, are detected by thephotodetector 26. When the photodetector 26 detects the interferencefringes, then the plane reflecting mirror 24 is moved in the ±Xdirections by the driving device 24 a provided on the plane reflectingmirror 24 under the control of the main control system 5, and thus thephase of the reference light is changed.

The information about the interference fringes detected by thephotodetector 26 is supplied to the signal processing system 27. Thesignal processing system 27 determines the three-dimensional positioninformation of the pinhole PH, i.e., the position in the X direction,the position in the Y direction, and the position in the Z direction ofthe pinhole PH based on the output of the photodetector 26.Specifically, the signal processing system 27 detects thetwo-dimensional position information (position in the X direction andposition in the Y direction) of the pinhole PH, for example, at a highaccuracy of not more than 1/1000 of the wavelength λ of the detectinglight based on the tilt components of the interference fringes obtainedby the interference fringe analysis. Further, the signal processingsystem 27 detects the focus position information (position in the Zdirection) of the pinhole PH, for example, at a high accuracy of notmore than 1/1000 of the wavelength λ of the detecting light based on thefocus components of the interference fringes obtained by theinterference fringe analysis.

An explanation will be made with reference to FIG. 8 about the principleof the detection of the two-dimensional position information of thepinhole PH. FIG. 8 conceptually shows, by broken lines, the pinhole PHprovided when the mask M is positioned at a desired position in the Xdirection and the Y direction. In this case, the position of the pinholePH in the X direction (and the Y direction) is coincident with anoptical axis 23 a of the light-collecting lens 23. A spherical wave SW₀,which is represented by broken lines, is generated about the center of aspherical center SC₀ thereof from the pinhole PH arranged at the desiredposition as described above. If the mask M is deviated from the desiredposition by ΔX in the X direction, the pinhole PH is also similarlydeviated from a position X₀ (optical axis 23 a of the light-collectinglens 23) to a position X₁. A spherical wave SW₁, which is generated fromthe pinhole PH positioned at the position X₁, is represented by solidlines in FIG. 8, and the spherical center thereof is represented by SC₁.As appreciated from FIG. 8, if the pinhole PH is deviated by ΔX in the Xdirection, the spherical center SC₁ of the spherical wave SW₁ is alsodeviated by ΔX from the optical axis 23 a of the light-collecting lens23. As a result, if the spherical wave SW₁ is viewed from the center ofthe light-collecting lens 23, the spherical wave SW₁ appears to travelnot from the direction of the optical axis 23 a but from a directioninclined with respect to the optical axis 23 a. In this way, thespherical wave SW₁, which comes into the light-collecting lens 23,cannot be a plane wave, in which the phases are uniformized in the planeperpendicular to the optical axis 23 a, when the spherical wave SW₁exits from the light-collecting lens 23. That is, the measuring lightexiting from the light-collecting lens 23 becomes a plane wave or aspherical wave which has its wavefront not perpendicular to the opticalaxis 23 a. As a result, the measuring light passing through the opticalaxis of the relay optical system 25 has the phase in the X directionwhich is different from the phase in the X direction of the measuringlight passing through any portion separated in the +Y direction and the−Y direction from the optical axis of the relay optical system 25. Ifthe measuring light as described above causes the interference with thereference light which is reflected from the plane reflecting mirror 24,the interference position differs in the X direction in the measuringlight. Therefore, a pattern, in which the brightness and the darknessdiffer between the center and the both side portions in the Y directionof the spot formed by being irradiated with the measuring light, i.e.,the interference fringe appears on the surface of the photodetector 27.FIG. 10 shows examples of the interference fringe patterns detected bythe photodetector 27. FIG. 10A shows an interference fringe patternobtained when the positional deviation of the mask M is absent, in whichthe entire surface is the brightness pattern. FIG. 10B shows aninterference fringe pattern obtained when the positional deviationarises in the X direction of the mask M, in which vertical fringes areobserved. Any one of FIGS. 10A to 10C shows the still image observed inaccordance with the fringe scan method as described later on.

Next, an explanation will be made with reference to FIG. 9 about theprinciple of the detection of the focus position information of thepinhole PH. FIG. 9 conceptually illustrates, by broken lines, theprinciple PH when the mask M is positioned at the desired position inthe X direction and the Y direction. In this case, the position of thepinhole PH in the X direction and the Y direction is located on theoptical axis 23 a of the light-collecting lens 23, and a position Z₀ ofthe pinhole PH in the Z direction is coincident with the desiredlight-collecting position of the light-collecting lens 23 (just focusposition). A spherical wave SW₀, which is depicted by broken lines, isgenerated about the center of a spherical center SC₀ thereof from thepinhole PH arranged at the desired position as described above. In thiscase, the spherical wave SW₀ is (becomes) a plane wave when thespherical wave SW₀ exits from the light-collecting lens 23; and thephase of the plane wave is coincident with the phase of the referencelight at any position in the plane perpendicular to the optical axis.Therefore, the plane wave and the reference light cause the interferencewith each other. As a result, the bright pattern as shown in FIG. 10A isobserved.

If the mask M is deviated by ΔZ in the −Z direction from the desiredposition in the Z direction, the pinhole PH is similarly deviated fromthe position Z₀ to a position Z₁. A spherical wave SW₂, which isgenerated from the pinhole PH positioned at the position Z₁, isrepresented by solid lines in FIG. 9, and the spherical center thereofis represented by SC₂. As appreciated from FIG. 9, if the pinhole PH isdeviated by ΔZ in the Z direction, the spherical center of the sphericalwave SW₁ is also deviated by ΔZ in the direction of the optical axis 23a of the light-collecting lens 23. Therefore, the spherical wave SW₂comes into the light-collecting lens 23 at a phase different from thatof the spherical wave SW₀. That is, when the spherical wave SW₂ exitsfrom the light-collecting lens 23, the spherical wave SW₂ is a planewave. However, the plane wave cannot become such a plane wave that allof the in-plane phases are uniformized in relation to the beam passingthrough the optical axis 23 a and those disposed at the outercircumferential portions of the beam; and the phase of the plane wave isnot coincident with the phase of the reference light at the in-planeposition perpendicular to the optical axis. As a result, the measuringlight beam (measuring light), which passes through the optical axis ofthe relay optical system 25, has the phase in the X direction which isdifferent from the phase in the X direction of the measuring light whichpasses through the portion (outer circumferential portion) separatedfrom the optical axis of the relay optical system 25. Therefore, thepattern, in which the brightness and the darkness differ between thecenter and the outer circumferential portion of the spot formed by beingirradiated with the measuring light, i.e., the interference fringeappears on the surface of the photodetector 27. FIG. 10C shows theinterference fringe pattern detected by the photodetector 27. FIG. 100also depicts the still image observed in accordance with the fringe scanmethod.

A brief explanation will be made below about the fringe scan method asan example of the interference fringe analysis to be performed by thesignal processing system 27. In this method, the information of theinterference fringes detected by the photodetector 26 is obtained insynchronization with the phase change of the reference light. The phaseof the reference light is changed by driving the driving device (forexample, piezoelectric element) 24 a of the plane reflecting mirror 24by the main control system 5 to move the plane reflecting mirror 24 inthe optical axis direction. For example, the driving device 24 a isdriven in accordance with a driving waveform which represents a drivingamount (d) with respect to a driving time (t) of the plane reflectingmirror 24 as shown in FIG. 12. FIGS. 13A to 13D show the change of theinterference fringe pattern detected by the photodetector 26 when theplane reflecting mirror 24 is moved in the optical axis direction byevery ¼ of the detecting light wavelength λ. The data of all pixels ofCCD constructing the photodetector 26 is obtained at the point in timeat which the plane reflecting mirror 24 is moved in the optical axisdirection by every ¼ of the detecting light wavelength λ. Theinterference fringes detected by the photodetector 26 are supplied tothe signal processing system 27. Assuming that I₁, I₂, I₃, I₄ representoutputs of a certain pixel at the driving amounts of 0, λ/4, λ/2, 3λ/4,the initial phase of the light coming into the pixel is determined byusing the following expression by the signal processing system 27.Φ₀=tan⁻¹(I ₂ −I ₄)/(I ₁ −I ₃)

The X/Y shift amounts and the focus amount (shift amount in the Zdirection) of the pinhole are determined for each of the pixels at ahigh accuracy of not more than 1/1000 of the detecting light wavelengthλ from the initial phase calculated as described above, NA of thelight-collecting lens 23, and the detecting light wavelength λ. Theinterference fringes may be observed and analyzed by using the shearingmethod in which the reflecting mirror is inclined without moving thereflecting mirror in the optical axis direction, instead of the fringescan method.

The three-dimensional position information of the pinhole PH detected bythe mask position detecting apparatus 11, consequently thethree-dimensional position information of the pattern surface of themask M, is supplied to the main control system 5. Actually, the maskposition detecting apparatus 11 independently detects thethree-dimensional positions of a plurality of (for example, three)pinholes PH provided on the pattern surface of the mask M. In this way,by detecting the three-dimensional positions of the three or morepinholes PH, the information about the rotation about the X axis and theY axis of the mask surface can be obtained from the position informationof the pinholes PH. The main control system 5 drives the mask stage MSbased on the detection result of the mask position detecting apparatus11, to thereby positionally adjust (align) the pattern surface of themask M in the X direction, the Y direction, and the direction ofrotation with respect to the projection optical system PL. Further, themain control system 5 drives the mask stage MS based on the detectionresult of the mask position detecting apparatus 11, if necessary, tothereby perform positional adjustment in relation to the leveling and inrelation to the Z direction for the pattern surface of the mask M withrespect to the projection optical system PL.

As shown in FIG. 3, the following situation is assumed for the maskposition detecting apparatus 11. That is, a regular reflected light L3,which is generated from the light-reflecting area 31 disposed around thepinhole PH by receiving the detecting light L1, arrives at thephotodetector 26, the regular reflected light L3 affects the formationof the interference fringes between the reference light and themeasuring light, and the regular reflected light L3 consequently affectsthe accuracy of the position detection. In such a situation, as shown inFIG. 4A, for example, it is preferable to additionally provide a lightshielding plate (light shielding member) 28 in the optical path betweenthe light-collecting lens 23 and the mask M in order that thephotodetector 26 is shielded from the arrival of unnecessary light L3which is generated from the light-reflecting area 31 disposed around thepinhole PH.

As shown in FIG. 4B, the light shielding plate 28 has, for example, arectangular form, and the light shielding plate 28 is arranged to shieldor intercept about a half of the detecting light L1 which will arrive atthe pattern surface of the mask M to form the spot light 32. In thiscase, a part of the diffracted measuring light L2, which is generatedfrom the pinhole PH, is shielded by the light shielding plate 29.However, it is possible to shield the unnecessary light (regularreflected light) L3 generated from the light-reflecting area 31 disposedaround the pinhole PH by the light shielding plate 28. As a result, itis possible perform the position detection highly accurately, withoutsubstantially being affected by the unnecessary light L3 which isgenerated from the surrounding of the pinhole PH by receiving thedetecting light L1.

It is preferable that the light shielding plate 28 is arranged at theposition optically conjugate with the detection surface of thephotodetector 26. Owing to this arrangement, it is possible to avoid theinfluence, exerted on the formation of the interference fringes betweenthe reference light and the measuring light on the photodetector 26, bythe diffracted light generated at an edge 28 a of the light shieldingplate 28 by receiving the detecting light L1, and it is possible toconsequently avoid the influence exerted on the accuracy of the positiondetection, for the following reason. That is, when the light shieldingplate 28 and the detection surface of the photodetector 26 are arrangedat the optically conjugate positions, the diffracted light, which isgenerated at the edge 28 a of the light shielding plate 28, is collectedagain on the detection surface of the photodetector 26. Therefore, anyfuzziness (out of focus) does not arise, which would be otherwise causedby the diffracted light.

The spherical center of the diffracted light generated from the pinholePH is not strictly determined by only the position of the pinhole PH,and is slightly affected by the light-collecting position of thedetecting light. For example, as shown in FIG. 4A, in the constructionin which about the half of the detecting light L1 coming into thepattern surface of the mask M is shielded by the light shielding plate28, the axis of the center of gravity of the incident light flux cominginto the pattern surface of the mask M is inclined toward the left side(in the −X direction) as viewed in the drawing. Therefore, if thedetecting light is defocused, the detecting light is deviated in the Xdirection with respect to the pinhole PH. As a result, the mask positiondetecting apparatus 11 erroneously detects, as the center position ofthe pinhole PH, a position which is moved from the center position ofthe pinhole PH by ΔH (amount proportional to the deviation of thedetecting light in the X direction) toward the left side (in the −Xdirection) as viewed in the drawing. In order to avoid the erroneousdetection, as shown in FIG. 4B, the following procedure may beappropriately adopted. That is, the position of the light shieldingplate 28 is switched between a first position (position indicated bysolid lines in the drawing) at which the right half of the detectinglight L1 which will arrive at the pattern surface of the mask M and formthe spot light 32 as viewed in the drawing is shielded and a secondposition (position indicated by broken lines in the drawing) at whichthe left half of the detecting light L1 as viewed in the drawing isshielded; and the center position of the pinhole PH is detected, forexample, based on the average value of the detection result obtained atthe first position and the detection result obtained at the secondposition.

The mask position detecting apparatus 11 described above uses therectangular light shielding plate 28 in which the position can beswitched along one direction. However, the present invention is notlimited to this. Various forms are conceivable in relation to the lightshielding member which is provided to shield the arrival at thephotodetector 26 of the unnecessary light L3 generated from thelight-reflecting area 31 disposed around the pinhole PH. For example, asshown in FIG. 5, a light shielding member 28′ can be also constructedsuch that apexes of three triangular light-shielding areas 28 b are madeto coincide with each other, and the three light-shielding areas 28 bare arranged substantially rotationally symmetrically in relation to aposition 28 c at which the apexes are coincident with each other. Thelight shielding member 28′ is realized, for example, by forming thelight-shielding areas 28 b on a light-transmissive substrate.

In a case that the light shielding member 28′ is used, the erroneousdetection of the center position of the pinhole PH, which would becaused by the shield of a part of the detecting light L1 coming into thepattern surface of the mask M, can be suppressed to be small, even whenthe position is not switched by moving the light shielding member 28′,because the three triangular light-shielding areas 28 b are arrangedsubstantially rotationally symmetrically in relation to the centerposition 28 c. By performing the position detection while rotating thelight shielding member 28′ at a high speed about the axis which passesthrough the center position 28 c and which is parallel to the Z axis, itis possible to suppress the erroneous detection of the center positionof the pinhole PH to be smaller, and consequently it is possible toperform the position detection more highly accurately. In a case thatthe light shielding member 28′ is used, it is also preferable that thelight shielding member 28′ is arranged at the position which isoptically conjugate with the detection surface of the photodetector 26in order to avoid the influence exerted on the formation of theinterference fringes by the diffracted light generated at the edge ofthe light-shielding area 28 b.

The mask position detecting apparatus 11 described above uses thepinhole PH which is constructed of a minute light-transmitting portionsurrounded by the light-reflecting area 31 on the pattern surface PP ofthe mask M, as the diffracted light generating portion which generatesthe diffracted measuring light by receiving the detecting light.However, the present invention is not limited to this. For example, itis also possible to use, as the diffracted light generating portion, apoint reflector (pin mirror) which is constructed of a minutelight-reflecting portion surrounded by a light-transmitting area on thepattern surface PP of the mask M. Further, for example, it is alsopossible to use, as the diffracted light generating portion, aprotrusion PR which has a reflecting surface (top portion) protruding tothe outside of the mask M from a surrounding area as shown in FIG. 11A,or a recess RE which has a reflecting surface (bottom surface) recessedto the inside of the mask M from a surrounding area as shown in FIG.11B, on the pattern surface PP of the mask M. Further, for example, itis also possible to use, as the diffracted light generating portion, adifferent reflectance portion (high reflective portion or low reflectiveportion) which has a reflectance different from that of a surroundingarea, on the pattern surface PP of the mask M.

Similarly, also in the wafer position detecting apparatus 13 of thisembodiment, the three-dimensional position information (position in theX direction, position in the Y direction, and position in the Zdirection) is detected for a plurality of (for example, three)diffracted light generating portions (for example, pinholes, pointreflectors, protruding stepped portions, recessed stepped portions,different reflectance portions, etc.) formed on the surface (exposuresurface) of the wafer W based on the output of the photodetector 26.Specifically, the signal processing system 27 detects thetwo-dimensional position information (position in the X direction andposition in the Y direction) of the diffracted light generating portionsprovided on the exposure surface of the wafer W, for example, at a highaccuracy of not more than 1/1000 of the wavelength λ of the detectinglight based on the tilt components of the interference fringes obtainedby the interference fringe analysis.

Further, the focus position information (position in the Z direction) isdetected for the diffracted light generating portions provided on theexposure surface of the wafer W, for example, at a high accuracy of notmore than 1/1000 of the wavelength λ of the detecting light based on thefocus components of the interference fringes obtained by theinterference fringe analysis. The main control system 5 drives the Zstage 2 based on the detection result of the wafer position detectingapparatus 12 to thereby perform the positional adjustment for theleveling and in the Z direction of the exposure surface of the wafer Wwith respect to the projection optical system PL. Further, the maincontrol system 5 drives the XY stage 3 based on the detection result ofthe wafer position detecting apparatus 12 to thereby perform thepositional adjustment of the exposure surface of the wafer W in the Xdirection, the Y direction, and the direction of rotation with respectto the projection optical system PL.

The mask position detecting apparatus 11 described above uses thephotodetector (area sensor) 26 such as CCD or the like as the detectorfor detecting the interference fringes formed by the interferencebetween the reference light and the measuring light. However, thepresent invention is not limited to this. For example, a transmittingscreen or a reflecting screen can be also used as the detector. In acase that the transmitting screen or the reflecting screen is used, itis possible to detect the three-dimensional position information(position in the X direction, position in the Y direction, and positionin the Z direction) of the diffracted light generating portion byobserving the interference fringes projected onto the screen.

In the mask position detecting apparatus 11 described above, theinformation about the interference fringes is detected by thephotodetector 26. However, the present invention is not limited to this.The information (position information about the spherical center of thediffracted light), which relates to the spherical center position of thediffracted light generated from the diffracted light generating portion,may be detected by the photodetector 26. That is, the deviation orexcursion of the intensity distribution of the diffracted light isdetected to make comparison, for example, with the intensitydistribution obtained when the just alignment position is provided.Accordingly, the spherical center position can be detected from thepositional deviation (lateral deviation) amounts in the X and Ydirections and the deviation amount in the Z direction (in the opticalaxis direction from the just focus position). More specifically, thespherical center position information of the diffracted light can bedetected as follows. In a case that the mask M is positioned at a(first) reference position by the mask stage MS, the diffracted light L2is generated from the hole (or the pin mirror) at the position as shownin FIG. 1. In this procedure, as described above, the interferencefringes, which are formed by the diffracted light L2 and the referencelight, are measured by the mask position detecting apparatus 11. Themeasured interference fringes are interference fringes to be observedwhen the mask M is positioned at the (first) reference position by themask stage MS; and the position of the mask M is measured by the masklaser interferometer MIF. If the position of the mask M is deviated fromthe (first) reference position, the interference fringes are observed asdescribed above. The interference fringes include the information aboutthe deviation amount of the spherical center. That is, it is possible toknow the positional deviation amount of the spherical center accordingto the tilt amounts (X/Y shift amounts are calculated from X/Y tiltamounts) and the defocus amount (Z) determined from the interferencefringes as described above. The position of the spherical center isobtained by adding the positional deviation amount of the sphericalcenter determined from the interference fringes to the positioncoordinate of the mask stage MS obtained when the mask M is positionedat the (first) reference position. During the process of thecalculation, the shift amounts and the focus amount are multiplied bycorrection coefficients depending on the measuring wavelength, the sizeand the depth of the pinhole, and NA of the light-collecting lens whicheffects radiation (irradiation) onto the pinhole.

As described above, the mask position detecting apparatus 11 of thisembodiment can detect the three-dimensional position information of thepattern surface of the mask M highly accurately in accordance with therelatively simple construction. Further, the wafer position detectingapparatus 12 of this embodiment can also detect the three-dimensionalposition information of the exposure surface of the wafer W highlyaccurately in accordance with the relatively simple construction. As aresult, in the exposure apparatus of this embodiment, the patternsurface of the mask M and the exposure surface of the wafer W can bepositionally adjusted (aligned) highly accurately with respect to theprojection optical system PL by using the position detecting apparatuses11, 12 for detecting the three-dimensional position information of thepattern surface of the mask M and the exposure surface of the wafer Whighly accurately. Consequently, it is possible to perform the exposuresatisfactorily.

In a case that the three-dimensional position information of theexposure surface of the wafer W is detected in accordance with thepresent invention, alignment marks provided on the respective shot areasdefined and comparted on the wafer surface and marks provided outsidethe shot areas can be formed with the pin mirrors or the protrudingpatterns as described above. As for such marks, for example, the pinholepattern of the mask can be transferred to the wafer by exposing thewafer W, which is coated with a photosensitive material, with a patternof the mask which is formed with the pinholes PH as described in theforegoing embodiment and by performing the development. The alignmentmark, which is formed on the wafer W, is usually detected by using analignment system of the off-axis system or an alignment microscope ofthe TTL system. However, in the present invention, it is possible tosimultaneously detect not only the two-dimensional position informationin the X and Y directions but also the position in the Z directioncorresponding to the focus information, by using the position detectingsystem as shown in FIG. 2 as described above. The main control system 5of the exposure apparatus can positionally adjust the respective shotareas in the X, Y, and Z directions with respect to the pattern of themask M in a short period of time by controlling the wafer stage drivingsystem 6 in the coordinate system of the wafer laser interferometer WIFby using the position information of the respective shot areas of thewafer W obtained as described above and the distance (baseline)information about the distance between the wafer position detectingapparatus 12 and the projection optical system PL provided with thesame.

In the embodiment described above, the mask position detecting apparatus11 is attached to the illumination system 1, and the wafer positiondetecting apparatus 12 is attached to the projection optical system PL.However, the present invention is not limited to this. Both of the maskposition detecting apparatus 11 and the wafer position detectingapparatus 12 can be attached to the projection optical system PL aswell. The mask position detecting apparatus 11 may be arrangedseparately or away from the illumination system 1, and/or the waferposition detecting apparatus 12 may be arranged separately or away fromthe projection optical system PL.

In the embodiment described above, the present invention is applied tothe mask position detecting apparatus 11 which detects thethree-dimensional position information of the pattern surface of themask M and the wafer position detecting apparatus 12 which detects thethree-dimensional position information of the exposure surface of thewafer W in the exposure apparatus. However, the present invention is notlimited to this. The position detecting apparatus of the presentinvention can be also used, for example, when the flatness of the waferbefore the exposure is measured on a calibration stage provideddistinctly from the wafer stage (2, 3). In this case, thethree-dimensional position information is detected for a plurality of(for example, three) diffracted light generating portions formed on thesurface of the wafer, and the flatness of the wafer is measured based onthe detected position information. Further, in general, the positiondetecting apparatus of the present invention is applicable to thedetection of the three-dimensional position information of any otherappropriate object other than the mask and the wafer. For example, theposition detecting apparatus of the present invention is also usable fora focus mechanism of a camera and usable for positional adjustment ofany sample for a microscope, without being limited to only the exposureapparatus.

In the embodiment described above, the light shielding plate 28 (28′) isused to shield the reflected light from the member disposed around thepinhole PH. However, the light shielding plate is not necessarilyindispensable in the present invention. In particular, the lightshielding plate is unnecessary in a case that the reflectance of thesurrounding of the pinhole PH is low and/or in a case that the pinmirror or any protrusion or recess having a reflecting surface having areflectance higher than that of the surrounding is used. It is notnecessarily indispensable that the position detector itself is providedwith the signal processing system 27. For example, the control system ofthe exposure apparatus may perform the signal processing. It is alsopossible to utilize a computer which is available at the site at whichthe position detection is performed. In the embodiment described above,the position of the reflecting mirror 24 in the optical axis directionis moved by using the driving device 24 a which drives the reflectingmirror. However, the frequency of the light source may be modulated,without using the driving device 24 a.

The foregoing embodiment has been explained as exemplified by theexposure apparatus having the structure as shown in FIG. 1 by way ofexample. However, the present invention is not limited to this, and thepresent invention is applicable to exposure apparatuses of varioustypes. For example, it is possible to adopt, for example, an exposureapparatus in which two mask patterns are combined on a substrate via aprojection optical system and one shot area on the substrate issubjected to the double exposure substantially simultaneously by onetime of the scanning exposure as disclosed, for example, in U.S. Pat.No. 6,611,316. It is possible to adopt, for example, an exposureapparatus of the proximity system and a mirror projection aligner as theexposure apparatus. It is also possible to adopt an exposure apparatusof the twin stage type provided with a plurality of substrate stages asdisclosed, for example, in U.S. Pat. Nos. 6,341,007, 6,400,441,6,549,269, 6,590,634, 6,298,407, and 6,262,796. It is possible to adoptan exposure apparatus provided with a plurality of substrate stages andmeasuring stages. The present invention is also applicable to a liquidimmersion type exposure apparatus in which a liquid immersion space isformed between a substrate and a projection optical system and a maskpattern is subjected to the exposure via a liquid supplied to the liquidimmersion space. In the liquid immersion exposure apparatus, the maskposition and the wafer position can be detected without allowing theliquid to intervene (not via the liquid).

As for the way of use of the exposure apparatus, the present inventionis not limited to the exposure apparatus for producing the semiconductorelement in which a substrate is exposed with a semiconductor elementpattern. The present invention is also widely applicable, for example,to exposure apparatuses for producing a liquid crystal display elementor producing a display as well as exposure apparatuses for producing,for example, a thin film magnetic head, an image pickup element (CCD), amicromachine, MEMS, a DNA chip, a reticle, or a mask.

In the respective embodiments described above, the position informationof each of the mask stage, the substrate stage, and the measuring stageis measured by using the interferometer system including the laserinterferometer. However, the present invention is not limited to this.It is also allowable to use, for example, an encoder system whichdetects a scale (diffraction grating) provided on each of the stages. Inthe respective embodiments described above, the ArF excimer laser may beused as the light source device or apparatus which generates the ArFexcimer laser beam as the exposure light. However, it is also allowableto use a high harmonic wave generator which includes, for example, asolid laser light source such as a DFB semiconductor laser, a fiberlaser or the like, a light-amplifying section having a fiber amplifieror the like, and a wavelength converting section and which outputs thepulse light having a wavelength of 193 nm as disclosed, for example, inU.S. Pat. No. 7,023,610.

With the exposure apparatus of the embodiment described above, anelectronic device (a semiconductor element, an image pickup element, aliquid crystal display element, a thin film magnetic head, etc.) can beproduced by exposing a photosensitive substrate with a mask pattern byusing the projection optical system (exposure step). An explanation willbe made below with reference to a flow chart shown in FIG. 6 about anexemplary procedure adopted when the semiconductor device as theelectronic device is obtained by forming a predetermined circuitpattern, for example, on a wafer as the photosensitive substrate byusing the exposure apparatus of the embodiment of the present invention.

At first, in Step S301 shown in FIG. 6, a metal film is vapor-depositedon each of wafers of 1 lot. Subsequently, in Step S302, a photoresist iscoated on a surface of the metal film on each of the wafers of 1 lot.After that, in Step S303, the exposure apparatus of the embodiment ofthe present invention is used to successively transfer and expose, viathe projection optical system, an image of a pattern on the mask to therespective shot areas on each of the wafers of 1 lot. After that, thephotoresist on each of the wafers of 1 lot is developed in Step S304,and then the etching is performed by using the resist pattern as a maskon each of the wafers of 1 lot in Step S305. Accordingly, a circuitpattern, which corresponds to the pattern on the mask, is formed on eachof the shot areas on each on the wafers.

After that, by forming circuit patterns of upper layers, etc., thedevice such as the semiconductor element or the like is produced.According to the method for producing the semiconductor device describedabove, the semiconductor device, which has an extremely fine circuitpattern, can be obtained with a good throughput. In Step S301 to StepS305, the metal is vapor-deposited on the wafer, and the surface of themetal film is coated with the resist to perform the respective steps ofthe exposure, the development, and the etching. However, it goes withoutsaying that a silicon oxide film may be formed on the wafer prior tothese steps, and then the surface of the silicon oxide film may becoated with the resist to perform the respective steps of the exposure,the development, and the etching.

With the exposure apparatus of the embodiment of the present invention,it is also possible to obtain a liquid crystal display element as theelectronic device by forming a predetermined pattern (a circuit pattern,an electrode pattern, etc.) on a plate (glass substrate). An explanationwill be made below with reference to a flow chart shown in FIG. 7 aboutan exemplary procedure adopted in this process. With reference to FIG.7, in a pattern forming step 401, a so-called photolithography step isexecuted, in which a mask pattern is transferred to a photosensitivesubstrate (for example, a glass substrate coated with a resist) toperform the exposure by using the exposure apparatus of the embodimentof the present invention. The predetermined pattern, which includes alarge number of electrodes, etc., is formed on the photosensitivesubstrate in accordance with the photolithography step. After that, theexposed substrate undergoes the respective steps including a developmentstep, an etching step, a resist exfoliation step, etc., and thus thepredetermined pattern is formed on the substrate; and the process nextproceeds to a color filter forming step 402.

Next, in the color filter forming step 402, a color filter is formed, inwhich a large number of sets of three types of dots corresponding to R(Red), G (Green), and B (Blue) are arranged in a matrix form, or aplurality of sets of filters of three types of stripes of R, G, and Bare arranged in the horizontal scanning direction. A cell assemblingstep 403 is executed after the color filter forming step 402. In thecell assembling step 403, a liquid crystal panel (liquid crystal cell)is assembled by using, for example, a substrate having the predeterminedpattern obtained in the pattern forming step 401 and the color filterobtained in the color filter forming step 402.

In the cell assembling step 403, for example, the liquid crystal panel(liquid crystal cell) is produced by injecting the liquid crystal into aspace between the substrate having the predetermined pattern obtained inthe pattern forming step 401 and the color filter obtained in the colorfilter forming step 402. After that, in a module assembling step 404,respective parts, which include an electric circuit, a backlight, etc.performing the display operation of the assembled liquid crystal panel(liquid crystal cell), are attached, and the liquid crystal displayelement is completed. According to the method for producing the liquidcrystal display element described above, the liquid crystal displayelement, which has the extremely fine circuit pattern, can be producedat a high throughput.

According to the position detecting apparatus of the present invention,the three-dimensional position information of the objective can bedetected highly accurately, although the position detecting apparatushas the relatively simple structure. The exposure apparatus of thepresent invention uses the position detecting apparatus of the presentinvention. Therefore, the pattern surface of the mask can bepositionally adjusted highly accurately with respect to the exposuresurface of the photosensitive substrate, although the alignment systemand the focus system has the simple structures. Therefore, according tothe method for producing the device of the present invention, it ispossible to produce the highly accurate electronic device. Therefore,the present invention will remarkably contribute to the internationaldevelopment of the precision mechanical equipment industry including thesemiconductor industry.

What is claimed is:
 1. A position detecting apparatus which detects athree-dimensional position of an object, the position detectingapparatus comprising: a light source which supplies a detecting light;light-collecting optics having at least one optical element whichcollects the detecting light onto a diffracted light generating portionassociated with a position of a surface of a predetermined pattern or anexposure surface of a photosensitive substrate, the diffracted lightgenerating portion including at least one hole, an uneven surface area,or a reflective surface; a reference surface defined by a plane mirroror a corner cube prism; light guiding optics having at least one opticalelement which guides, to a predetermined position, a diffractedmeasuring light generated from the diffracted light generating portionby receiving the detecting light and a collimated reference lightgenerated from the reference surface by receiving the detecting light; aphotodetector which is arranged at the predetermined position and whichdetects interference fringes generated by the diffracted measuring lightand the collimated reference light; an interference fringe analyzercoupled to the photodetector so as to detect, as the three-dimensionalposition of the object, a three-dimensional position of the surface ofthe predetermined pattern or the exposure surface of the photosensitivesubstrate; and a stage which aligns the surface of the predeterminedpattern or the exposure surface of the photosensitive substrate based ona detection result of the interference fringe analyzer.
 2. The positiondetecting apparatus according to claim 1, further comprising thediffracted light generating portion, wherein the diffracted lightgenerating portion has a light-transmitting portion which is surroundedby a light-reflecting area, or a light-reflecting portion which issurrounded by a light-transmitting area.
 3. The position detectingapparatus according to claim 1, further comprising the diffracted lightgenerating portion, wherein the diffracted light generating portion hasa protruding stepped portion which protrudes from a surrounding area, ora recessed stepped portion which is recessed from a surrounding area. 4.The position detecting apparatus according to claim 1, furthercomprising the diffracted light generating portion, wherein thediffracted light generating portion has a different-reflectance portionwhich has a reflectance different from that of a surrounding area. 5.The position detecting apparatus according to claim 1, furthercomprising a light shield which shields the photodetector from arrivalof an unnecessary light generated from a surrounding of the diffractedlight generating portion by receiving the detecting light.
 6. Theposition detecting apparatus according to claim 5, wherein the lightshield is arranged at a position which is optically conjugate with thephotodetector.
 7. The position detecting apparatus according to claim 5,wherein the light shield is rotationally symmetric.
 8. The positiondetecting apparatus according to claim 5, wherein the light shieldincludes three triangular light-shields having coincident apexes.
 9. Theposition detecting apparatus according to claim 1, wherein the referencesurface is a reflecting surface, and an actuator, which moves thereflecting surface, is provided on the reflecting surface.
 10. Anexposure apparatus which exposes a photosensitive substrate with apredetermined pattern via a projection optical system, the exposureapparatus comprising: the position detecting apparatus as defined inclaim 1, wherein the stage is operable to align the surface of thepredetermined pattern or the exposure surface of the photosensitivesubstrate with respect to the projection optical system based on thedetection result of the position detecting apparatus.
 11. A positiondetecting method for detecting a position of an object, the positiondetecting method comprising: collecting a detecting light onto adiffracted light generating portion provided on the object; detectinginterference fringes generated by a diffracted measuring light generatedfrom the diffracted light generating portion by receiving the detectinglight and a collimated reference light generated from a referencesurface by receiving the detecting light, the reference surface beingdefined by a plane mirror or a corner cube prism; determiningthree-dimensional position information of the diffracted lightgenerating portion based on the interference fringes; and aligning theobject based on the three-dimensional position information.
 12. Theposition detecting method according to claim 11, further comprisingshielding an unnecessary light generated from a surrounding of thediffracted light generating portion by receiving the detecting light.13. The position detecting method according to claim 11, furthercomprising detecting the interference fringes while changing a phase ofthe reference light.
 14. The method of claim 11, wherein: the collectingthe detecting light onto a diffracted light generating portion comprisescollecting the detecting light onto a plurality of diffracted lightgenerating portions provided on the object; the detecting interferencefringes generated by a diffracted measuring light comprises detectinginterference fringes generated by the diffracted measuring lightgenerated from the plurality of diffracted light generating portions byreceiving the detecting light and the collimated reference lightgenerated from the reference surface by receiving the detecting light;and the determining three-dimensional position information comprisesdetermining three-dimensional position information of the diffractedlight generating portions based on the interference fringes associatedwith the plurality of diffracted light generating portions.
 15. Themethod of claim 11, wherein the diffracted light generating portion is apinhole, a point reflector, different reflectance portions, aprotrusion, or a recess.
 16. The method of claim 11, further comprisingsituating a light shield so as to be optically conjugate with thediffracted light generating portion.
 17. The method of claim 16, whereinthe light shield is situated so as shield about one-half of thediffracted light generating portion from the detecting light.
 18. Themethod of claim 16, wherein the light shield is rotationally symmetricabout the diffracted light generating portion.
 19. The method of claim11, further comprising: situating a light shield at first and secondpositions that are optically conjugate to the diffracted lightgenerating portion; the detecting interference fringes generated by adiffracted measuring light comprises detecting interference fringesgenerated by the diffracted measuring light associated with the firstand second positions; and the determining three-dimensional positioninformation comprises determining three-dimensional position informationof the diffracted light generating portion based on the interferencefringes associated with the first and second positions.
 20. A method forproducing a device, comprising: detecting, as a position of an object, aposition of a surface of a predetermined pattern or an exposure surfaceof a photosensitive substrate using a position detecting method asrecited in claim 11; exposing the photosensitive substrate with thepredetermined pattern; and developing the exposed photosensitivesubstrate.
 21. A position detecting apparatus which detects athree-dimensional position of an object, the position detectingapparatus comprising: a light source which supplies a detecting light;light-collecting optics having at least one optical element whichcollects the detecting light onto a diffracted light generating portionassociated with a position of a surface of a predetermined pattern or anexposure surface of a photosensitive substrate, the diffracted lightgenerating portion including at least one hole, an uneven surface area,or a reflective surface; a reference surface defined by a plane mirroror a corner cube prism; light guiding optics having at least one opticalelement which guides, to a predetermined position, a diffractedmeasuring light generated from the diffracted light generating portionby receiving the detecting light and a collimated reference lightgenerated from the reference surface by receiving the detecting light; aphotodetector which is arranged at the predetermined position and whichdetects interference fringes generated by the diffracted measuring lightand the collimated reference light; and a stage which aligns the surfaceof the predetermined pattern or the exposure surface of thephotosensitive substrate based on the detected interference fringes.